The true prevalence of Eprex® resistance is not known in Canada. It is estimated to be approximately 10% based on the early Eprex® therapy trials. The Canadian Nephrology Practice Patterns Study (CNPPS), which collected data on a large subset of Canadian dialysis patients from 1995 to 1998 provides some further estimates. Several authors have analyzed the CNPPS data and applied Eprex® resistance measures to this study population. Using the dose cut off point of >200units/kg/week of Eprex®, the authors found that the prevalence of Eprex® resistance was 15.7% for hemodialysis (HD) patients and 5.5% for peritoneal dialysis (PD) patients. Further analysis using the Eprex®/Hct measure showed a significant negative correlation between Eprex®/Hct and serum albumin in both HD and PD patients. Body mass index (BMI) was also positively correlated with Eprex®/Hct in both groups. This study also found that when the dose cut off of >200units/kg/week was utilized as a measure of exogenous erythropoietin resistance, 15% of the HD patients above this cut off point were utilizing 34% of all the Eprex® administered to HD patients in the study period. Similarly, 5.5% of Eprex® resistant PD patients required 16.2% of all the Eprex® given to PD patients during the same period.